With the advent of new network applications and services, end users are demanding high bandwidth end-to-end connections that need to be provisioned automatically and dynamically. An end-to-end connection may need to cross networks which belong to different operators. Typically, each operator manages their network independently of other operators. Each independently-operated network is called an Autonomous System (AS) or a domain. A network comprising a set of Autonomous Systems is called a multi-domain network.
The routing strategies applied within a single domain cannot be simply applied to a multi-domain scenario because of the scalability problems that arise in very extensive and complex topologies. The amount of topology information to be distributed and the frequency of updates would increase the overhead of the entire network signalling and thus the bandwidth request and the computational power consumed. In addition, there can be commercial reasons that prevent a domain administrator from sharing full details of their intra-domain topology with another domain administrator.
Although it is desirable to limit the amount of topology information that is shared between domains, it is also desirable that domains share sufficient information about their domains to allow efficient traffic engineering across a multi-domain network.
A further complication in a multi-domain network is that different domains within the multi-domain network may use different technology types. Possible technology types include packet-based transport and optical technologies such as wavelength-switched optical networks (WSON).
A further complication is that a single domain within the multi-domain network can itself use multiple technology types. This kind of domain will be called a multi-layer domain and can have, for example, a packet-switched layer and a wavelength-switched layer. This kind of domain can also have a multi-layer control plane which controls both technology types, such as a GMPLS multi-layer control plane. A still further complication is that a multi-layer domain can comprise internal nodes with different switching capability (e.g. packet and WSON) and border nodes having just one switching capability (e.g. WSON). For the sake of scalability and confidentiality it is desirable not to advertise the internal topology. Moreover multi-layer networks can be composed by technologies with different features that make the routing complex if it is performed concurrently. For example in case of packet over WSON, due to different granularity and constraints of the two technologies, different routing methods could be considered.
The present invention seeks to provide a way of sharing topology information in a multi-domain, multi-technology, network.